THE EFFECT OF ENVIRONMENT ON THE MECHANICAL BEHAVIOR OF MATERIALS.
Abstract
The surface layer stress of high purity aluminum is lower in vacuum than in air. The relaxation rate, however, is faster in vacuum. The cyclic creep and work hardening rates of high purity and 1100 aluminum are lower in vacuum than in air. These observations are in accord with the concept that cyclic creep and cyclic hardening are controlled by the surface layer and not by the bulk of the material. Data on copper show that decreasing the surface layer stress increases the fatigue life. The difference in fatigue behavior in vacuum and air is caused by the difference in the surface layer stress. It is expected that the fatigue cracks will be initiated when the surface layer stress in a local region reaches a critical value equal to the fracture strength. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1968
- Accession Number
- AD0684580
Entities
People
- Irvin R. Kramer
Organizations
- Martin Marietta